Caravan Solar Panels
In the simplest of terms, solar panels work by converting sunlight into electrical energy. The basic element of a solar panel consists of a bonded pair of silicon wafers on a conductive backing, one called the ‘P’ layer and the other the ‘N’ layer. The photons of light interact with this PN substrate and a potential difference of approximately 0.6V is generated.
A typical solar panel comprises 32 to 36 such elements electrically connected in series thereby producing a panel with an open circuit voltage of 18V to 22V. The silicon material used in the panel comes in three basic forms, monocrystalline silicon, polycrystalline silicon and amorphous silicon.
Solar for Caravans
Mono-crystalline silicon is grown as one large crystal and subsequently cut into thin slices to form the individual cells. Panels made this way are a little more efficient, around 14-16%, but are also more expensive to produce. These panels usually comprise 34 to 36 elements producing 20V to 22V open circuits.
Solar for Caravans
Polycrystalline silicon is cast in blocks and the final cut slices consist of many smaller crystals. Manufacturing costs are lower, therefore these panels are a little cheaper to purchase. While the efficiency is a little lower, around 12-14%, the low angle light output can be higher, but they generally do not perform quite as well as monocrystalline types at higher panel temperatures.
Solar for Caravans
Amorphous silicon panels are produced by a completely different and cheaper process by depositing a vaporised silicon directly on to a backing material. This results in a cheaper panel but the efficiency is half that of mono or polycrystalline types, around 6%. This means you need twice the panel surface area to achieve the same output. They do have one advantage however, the amorphous silicon can be applied to a flexible backing such as plastic or thin stainless steel to result in a flexible panel with the ability to be laid on a curved surface. However, these flexible panels usually have a poor watt to dollar ratio.
Caravan Solar Panels are a great alternative power supply. Solar Panels allow you to camp anywhere whilst still having reliable power to keep lights on and run electrical devices.
Solar Panels come in various shapes and sizes to suit any caravan, camper or RV. They can be portable or mounted. Usually most larger caravans will have the panels mounted to the roof.
When mounting the solar panels on the roof of a caravan, it is a good idea to get this done by a professional, as they are subject to a lot of movement and high winds when travelling.
When you install solar panels to your van it keeps your caravans batteries charged. If you install a quality system they will last for decades and require little to no maintenance.
To store the energy generated by solar panels you will require solar batteries. The size of the solar battery you get depends on the length of your trip, how much power you will need and how many appliances you will need to run at once.
Most caravans have a 12, 24 or 48-volt battery system which is charged whilst towing, by the vehicle’s alternator using a charging unit.
With solar panels you will also need to insert a power regulator between the panel and the battery. We recommend using a quality regulator that automatically disconnects the battery from the panel when it is fully charged, to prevent it from overcharging.
Getting the right solar panel for your caravan and installing it correctly are the keys to ensuring you get enough power for everything you need to do when you’re out on the road.
Solar panels are available in a variety of sizes. The larger the panel size or area, the greater the electrical output. Common sizes range from 5W to 185W. The maximum output will only be achieved when the panel is pointing directly at the sun and the panel temperature is 25°C or less. Since our panel will be mounted horizontally, we will never quite see the full output as shown in the table below.
| Angle of Sun to Panel | % of Rated Output |
| 90° | 100% |
| 75° | 95% |
| 45° | 75% |
| 30° | 50% |
As the table suggests, the actual output of your panels is dependent not only on the time of day, but on your latitude as well. For instance, the same panels in Cairns (latitude of 17°S) at midday will be producing around 90-95% of the panel’s maximum output. However, if you were to use these same panels in Hobart (latitude of 43°S), the performance at midday would decrease to around75% of maximum output. Of course, these figures are only approximated and depend on many factors, including the type of panel you’re actually using.
Also bear in mind that during the cooler months, the Sun’s zenith is lower in the sky (which yields a greater angle to the panel), and the days are much shorter which will result in approximately half as many Ah that can be collected during any given day.
You may be asking yourself at this point, “Do I really need one?” While there is not a definitive answer, it does depend on two factors — the size of the panels you’re drawing from and the size of the battery you intend to send charge to.
Conditions for not requiring a charge regulator:
Because of their design, self-regulating panels (which will put out around a claimed 15V or so by design) have fairly limited applications in caravanning scenarios, and most applications will benefit from an externally-regulated solution.
Installing a charge regulator in conjunction with the larger 36-cell type panels has several advantages: firstly, it will provide faster charging of batteries; secondly it will require much less maintenance and yield much longer battery lifetimes; thirdly, it will collect far more Ah every single day. When it comes to choosing a solar regulator for your application, there are several features which will definitely benefit you in application. These include:
Don’t hesitate to call AllBrand for any of those questions you may have about harnessing the Sun’s rays or to make a booking with us.
In this application, it’s recommended you select at least an 80W panel, or, alternatively, the largest panel that will fit on the available roof of your rig. Skimping on panel size in the first instance may seem wise based on cost analysis, however it is something you will likely soon come to regret. As mentioned, a 75W panel can generate approximately 4-4.5A at maximum, or more useful to us, around 10 to 20Ah/day. That said, the more panels you have in your system, the greater energy can be generated in the same amount of time.
If you are using a compressor-type refrigerator in your rig (particularly anything larger than the smallest of portable units), you will likely need to increase this recommendation to at least 3, ideally 4 75-85W panels if your goal is to maintain long-term self-sufficiency on the road. Below this recommendation and you will find the system begins to struggle during times of cloud or high ambient temperature. Also remember that beyond refrigerators there are a number of things which will draw power from the system, including TVs, pumps, power inverters, and even your lighting.
Don’t hesitate to call AllBrand for your solar questions and needs, or to make a booking.
Below is the manufacturer-supplied data which accompanies a typical 80W panel:
| Nominal Peak Power | 75.00W |
| Open Circuit Voltage | 21.40V |
| Peak Power Voltage | 17.00V |
| Short Circuit Current | 4.75A |
| Peak Power Current | 4.45A |
| Minimum Power | 71.25W |
Specifications for 80W PV Cell
This information is oftentimes misleading – which in itself can lead to consumers ending up with grossly undersized arrays for their needs. The way in which we derive the actual rating for the panel is by multiplying the peak power voltage (in this case, 17V) and the peak power current (here it’s 4.45A) together, yielding a result of 75.65W. However, based on the formula to find power (W = V*A) many systems will claim to be capable of producing a much higher peak power current than the PV cells are actually capable of (because as voltage decreases, current increases proportionally for the same total power output). This means that on a 12V system, if you fall victim to this logic your system could be more than 40% undersized for your application.
Another thing to keep in mind is that these figures are derived under STC (25ºC/100kPa) with absolutely ideal irradiance and spectrum for the panels – in the real world their performance will be much below this rating as light will be less intense, and temperature on the surface of the PV cell will be far above the ideal (as surface temperature increases, efficiency of the panel drops significantly). Your angle to the sun will also likely be very different from the laboratory condition which introduces further losses.
To realistically approximate your system’s output capacity, the following formula should provide a fairly accurate picture. (PC * h * 0.5), where PC is the peak power current of the panel, h is the total number of hours where the sun will shine during any given day, and 0.5 being the realistic inefficiency factor of the system. This assumes a flat distribution of the panels, more ideal angling towards the sun will yield better results. While the cooler months bring with them much shorter daylight periods, they also bring a much cooler temperature which means the panels should experience a drop in surface temperature, and also, that high-draw appliances such as compressor fridges need to kick in much less of the time. It becomes a huge game of trade-offs, which is why it’s important to get the very best system to begin with. If you suspect this may present a problem, you may well be better off looking at a 3-way absorption-type fridge which will accept 12V, 240V, and gas inputs.
Mono-crystalline silicon is grown as one large crystal and subsequently cut into thin slices to form the individual cells. Panels made this way are a little more efficient, around 14-16%, but are also more expensive to produce. These panels usually comprise 34 to 36 elements producing 20V to 22V open circuits.
Polycrystalline silicon is cast in blocks and the final cut slices consist of many smaller crystals. Manufacturing costs are lower, therefore these panels are a little cheaper to purchase. While the efficiency is a little lower, around 12-14%, the low angle light output can be higher, but they generally do not perform quite as well as monocrystalline types at higher panel temperatures.
Amorphous silicon panels are produced by a completely different and cheaper process by depositing a vaporised silicon directly on to a backing material. This results in a cheaper panel but the efficiency is half that of mono or polycrystalline types, around 6%. This means you need twice the panel surface area to achieve the same output. They do have one advantage however, the amorphous silicon can be applied to a flexible backing such as plastic or thin stainless steel to result in a flexible panel with the ability to be laid on a curved surface. However, these flexible panels usually have a poor watt to dollar ratio.
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